Custom Fan Setup - Battery questions (18650, RCR123)
Good day all,
I have been lurking here for a while and thought it was time to join up to see if I could get opinions/answers to some of my questions. I apologize now that my needs are not geared towards flashlight uses but everytime I have tried to track information down, my research has sent me here. I really appreciate how awesome this forum is as a resource. Now with that out of the way:
I am constructing a cooling/de-fogging fan system for goggles. The system consists of 4 Sunon brand fans (3x 25mm, 1x 30mm) with the following technical specs:
25mm (ea) - 5VDC 0.08 Amps, 0.4 W (x3)
30mm (ea) - 5VDC 0.10 Amps, 0.5 W (x1)
Combined: 0.340 Amps, 1.7 W (Powered at roughly 75% = 0.255 A, 1.275 W)
I intend to use a 3.6V or 3.7V power system which will operate the fans at roughly 75% capacity which gives an ohm rating for the whole system of 13.49. This system will be mounted on a paintball mask and the batteries will be either mounted on the forehead or back of the head strap. Obviously safety is a huge concern given battery proximity, I have read the safety articles on Battery University as well as some of the warnings and cautions here. If the kit was just for myself I would be less concerned with charging and use but I am making these kits as well for some less than diligent people.
My goal is a safe kit that can give me at the very minimum a 2 hour runtime and I can tell the other users to simply charge the batteries when done. The safety of LiMn cells seems to be the best in this application but battery size and capacity are the sticking points. I am either going to use 18650's or CR123's and would prefer to purchase the highest capacity possible. Battery Station and AW are the preferred/reputable brands and a Pila IBC charger will be purchased for 18650's (if rechargables are the route taken) and I am still researching a charger for the 123's (probably the Tenergy on BatteryStation's website). These battery sizes are also in the running since I need home use/camping flashlights and would like them to perform double duty. The batteries for the fan system will be used once a week for about 6-8 hours half of the year; flashlight use will be minimal/rare.
18650's will use a separate cell holder externally, wired to the power switch; whereas the RCR123's would probably end up mounted on the PCB along with the dipswitch bank located at the inside front cheek of the mask for protection. I would like to use 123's for size but worry about capacity and the prohibitive cost associated with my desired runtime. I wish I could use non-rechargeables and buy a bulk lot of BatteryStation/Panasonic/Streamlight since they have a higher current capacity but all the ones I have seen are 3V. The 18650 though could be bought at 2900mah (AW) and would probably last me the day vice using two or three 900mah 123's.
Sorry for the wall of text on my first post; the long and short of it is:
18650 vs RCR123's for my systems needs?
LiCo, LiFePo or LiMn for safety concerns? (pretty sure I know the answer but thought I would ask).
Are my calculations correct and would a runtime of 3 hours be feasable with the Battery Station 900mah 3.7V RCR123s (2 - 2.5 hours with AW IMR 750mah for safety reasons?).
I am mainly looking at cost vs runtime for LiMn since I can buy 2 AW IMR 1600mah (unprotected) plus Pila charger for $70 +S&H, or a 123 charger for $10-20 and avg. of $6 a battery for Protected AW LiCo 750mah or Unprotected AW IMR 123s 550mah. I won't skimp on chargers or protected batteries due to safety but would still like to keep cost down.